Halotolerance of Rhodobacter sphaeroides for saline and hypersaline wastewater bioremediation

Hypersaline wastewaters require the continuous development of new and inexpensive alternatives for bioremediation. Halotolerant bacteria, which tolerate and are able to survive in moderate to high salinity environments, have been explored with promising results for wastewater treatment. Purple photosynthetic bacteria, a wide class of phototrophs, possess extraordinary metabolic versatility and include extremophiles that thrive in habitats having extreme pH, salinity, and light. The ability to grow under extreme environmental conditions of Rhodobacter (R.)sphaeroides, a purple non-sulfur proteobacteria that typically inhabits freshwater was evaluated. To investigate the response of R. sphaeroides to increased medium osmolarity under anerobic growth conditions, media with elevated osmotic strengths were attained by adding NaCl into the growing media at the desired concentrations in the range 0-2.5 M NaCl. Moreover, the pH effect on anaerobic growth was evaluated.